package com.java8.optional;

import java.util.Optional;

public class Main {
	public static void main(String args[]){
		   
		Main java8Tester = new Main();
	      Integer value1 = null;
	      Integer value2 = new Integer(10);
	        
	      // Optional.ofNullable - 允许传递为 null 参数
	      Optional<Integer> a = Optional.ofNullable(value1);
	        
	      // Optional.of - 如果传递的参数是 null，抛出异常 NullPointerException
	      Optional<Integer> b = Optional.of(value2);
	      System.out.println(java8Tester.sum(a,b));
	   }
	    
	   public Integer sum(Optional<Integer> a, Optional<Integer> b){
	    
	      // Optional.isPresent - 判断值是否存在
	        
	      System.out.println("第一个参数值存在: " + a.isPresent());
	      System.out.println("第二个参数值存在: " + b.isPresent());
	        
	      // Optional.orElse - 如果值存在，返回它，否则返回默认值
	      Integer value1 = a.orElse(new Integer(0));
	        
	      //Optional.get - 获取值，值需要存在
	      Integer value2 = b.get();
	      return value1 + value2;
	   }
}
